Tororider, thank you. Want to reply to some of your questions to provide more detail;
It may be in your best interest to go to a couple tree farms and see how they do things. Agree very much. Have one a few miles from me that I think would be willing to share info with me as I know one of the owners. Then it may depend on business.
If you do a little research you can find a ton of farms around that sell seedlings of all sorts. We have planted about 1000 trees over the past couple years, all conifers. The first year we used a transplanter to plant about 700 and with our soil is was more trouble than it was worth. Ended up with clumps and not being able to use the seat. We had to walk behind the tractor and step down the slit. Understand the problems with the setter or planter. Have old style tobacco setter which is very similar to tree model that I think can be remodeled to work. But those do not work in real wet dirt. Normally the dirt is bedded up first.
Last year we used a post hole digger and predug the holes. A little more time on the front end, and back end for that matter, but ended up with much better holes. Sure hope to avoid this method.
Is there water on site? Our first summer was extremely dry and there was no water on site so we ended up lugging 300 gallons at a time in the back end of our F250. It got really old really fast. Part of the reason we needed so much water was the holes weren't very good, because of the transplanter, and they lost moisture quickly. We have sources of water but all would require plumping or hauling. One is pond and other is well water. Could put in well for watering or dig pond right at the planted area also.
I know a lot of the seedling farms grown in pretty much all sand so that they can transplant easier, but I believe a lot of that is done in greenhouses.
If you are planning on selling full size trees and shrubs you will need to figure out if you are going to dig them out yourself or hire it out. If you are going to do it yourself you will need to get a tree spade. Full size would take a few years on trees we have in mind, but understand the need for digging equipment to match the tree.
I am sure others with more experience will chime in as well. I think John Bud has a large tree farm so he may be able to shed more light.
Any idea on how far apart width wise to have your rows? My quick thought is 6 feet but then could not run full size tractor between the rows. So do I need to go to wider rows, depend of compact tractor, or plant say two rows and skip the third row?
Again thank you all.